IP telephony services have become widely available through personal computers and specially developed IP telephony devices. Moreover, personal computers and specially developed IP telephony devices generally offer many additional services and enhanced functionality not offered by traditional mobile handsets (e.g., cellular phone). Nevertheless, in a world that is focused on mobility and progressive complexity, there is a rising need for utilizing the latest advances in IP telephony services while remaining mobile, especially in an enterprise context.
For example, as enterprises grow and spread, there are more companies outfitted with an in-house IP telephony system covering the offices, while requiring their employees to carry mobile handsets such as cellular phones and/or personal digital assistants (PDA) for personal contact and for staying in touch while on the move. However, as mentioned above, many traditional mobile handsets can not access the additional services and enhanced functionality offered by personal computers and specially developed IP telephony devices.
In response, recently, dual-mode cellular/wireless fidelity phones (dual-mode cellular/WiFi phones) capable of working both within the cellular network and within an enterprise Internet Protocol Private Branch exchange (IP PBX) have been created. However, generally these dual-mode cellular/WiFi phones are relatively limited in terms of functionality, storage capacity, connectivity and compatibility with current networked applications and data sources as compared against personal computers and specialized IP telephony devices.
In particular, these dual-mode cellular/WiFi phones are generally not able to access the additional services and enhanced functionality available to many personal computers and specialized equipment without expensive hardware changes that usually require complex hand-off designs. Furthermore, the hardware modified dual-mode cellular/WiFi phones capable of accessing the additional services and enhanced functionality of specialized equipment are typically complex, expensive and suffer from high power consumption. To exacerbate the problem, they often rapidly become obsolete as technology advances.